Class Ref

django/db/models/expressions.py:1447–1485

Reference to column alias of the query. For example, Ref('sum_cost') in qs.annotate(sum_cost=Sum('cost')) query.

class Ref(Expression):
    """
    Reference to column alias of the query. For example, Ref('sum_cost') in
    qs.annotate(sum_cost=Sum('cost')) query.
    """

    def __init__(self, refs, source):
        super().__init__()
        self.refs, self.source = refs, source

    def __repr__(self):
        return "{}({}, {})".format(self.__class__.__name__, self.refs, self.source)

    def get_source_expressions(self):
        return [self.source]

    def set_source_expressions(self, exprs):
        (self.source,) = exprs

    def resolve_expression(
        self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False
    ):
        # The sub-expression `source` has already been resolved, as this is
        # just a reference to the name of `source`.
        return self

    def get_refs(self):
        return {self.refs}

    def relabeled_clone(self, relabels):
        clone = self.copy()
        clone.source = self.source.relabeled_clone(relabels)
        return clone

    def as_sql(self, compiler, connection):
        return connection.ops.quote_name(self.refs), ()

    def get_group_by_cols(self):
        return [self]


class ExpressionList(Func):